1918] NOYES, TROST, & YODER—ROOT VARIATIONS 367 
shows representative roots where no carbon dioxide gas was applied. 
The roots were uniformly long and fibrous and extended to the 
bottoms of the culture pots. Representative roots grown where 
the carbon dioxide treatment was 8 hours per day are shown in 
fig. 4. These roots did not penetrate to a depth lower than 7 
inches. They were clumped and coarser when compared with 
those to which no carbon dioxide treatment was given. Aérial 
roots were quite prominent, and the main root was very thickly 
Fic. 2.—Capsicum annuum abbreviatum 4 months after carbon dioxide gas 
treatments were started: row of pots fronted by no. 11 received constant carbon 
dioxide treatment; row fronted by no. 8 received 8 hours’ aakeyy dioxide treatment 
daily; row fronted by no. 3 received no carbon dioxide treatmen 
set with branching roots at a depth of about 3 inches. The roots 
shown in fig. 5 are representative of those that grew when the 
carbon dioxide treatment was constant. They compare unfavor- 
ably with those obtained under no treatment and under intermittent 
treatment. Aérial roots are many and prominent. The main 
roots are dwarfed and coarse and irregular. No roots were found 
at a depth lower than 5 inches. The carbon dioxide gas added to 
soil growing the Christmas pepper caused abnormal root devel- 
opments. The gas had a much greater effect on the root devel- 
opment of the pepper plant than was apparent in the aérial 
portions. 
